Methods and formulations for superhydrophic, self-cleaning, and icephobic polymer coatings and objects having coatings thereon

ABSTRACT

An object has a superhydrophic, self-cleaning, and icephobic coating includes a substrate and a layer disposed on the substrate, the layer resulting from coating with a formulation having an effective amount of microstructuring microparticles, liquid silane having one or more groups configured to graft to a microstructuring microparticle and at least another group that results in hydrophobicity. The microstructuring microparticles are dispersed in the liquid silane. Another effective amount of synthetic adhesive, selected from thermosetting adhesives, moisture curing adhesives or polymers that form a strong interaction with a surface, is in solution with a solvent. Upon curing, the layer has a contact angle greater than 90° and a sliding angle of less than 10° and, less than 5% of an area of the layer is removed in a Tape test.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/542,108, entitled METHODS AND FORMULATIONS FOR SUPERHYDROPHIC,SELF-CLEANING, AND ICEPHOBIC POLYMER COATINGS AND OBJECTS HAVINGCOATINGS THEREON, filed on Nov. 14, 2014, and claims priority of U.S.Provisional Application Ser. No. 61/981,426, METHODS AND FORMULATIONSFOR SUPERHYDROPHIC, SELF-CLEANING, AND ICEPHOBIC POLYMER COATINGS ANDOBJECTS HAVING COATINGS THEREON, filed on Apr. 18, 2014, and of U.S.Provisional Application Ser. No. 62/079,632, METHODS AND FORMULATIONSFOR SUPERHYDROPHIC, SELF-CLEANING, AND ICEPHOBIC POLYMER COATINGS ANDOBJECTS HAVING COATINGS THEREON, filed on Nov. 14, 2014, all of whichare herein incorporated by reference in their entirety and for allpurposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made partially with U.S. Government support from theNational Science Foundation under the Nanoscale Science and EngineeringCenters program (Award: NSF-0832754). The U.S. Government has certainrights in the invention.

BACKGROUND

This invention relates generally to superhydrophic, self-cleaning, andicephobic polymer coatings, and, more particularly, to durablesuperhydrophic, self-cleaning, and icephobic polymer coatings.

The surface build up of ice, or ice accretion, and ice adhesion tovarious surfaces, have been a consistently undesirable occurrence oninfrastructure in high altitude and cold regions. The infrastructureaffected by ice includes, but is not limited to, wind turbines, powerlines, aircrafts, naval vehicles, and buildings. Associated costs withice accretion and ice adhesion include ice removal, inefficientoperation, aerodynamic instabilities, and safety hazards. Currentmethods of ice removal are characteristically separated by active andpassive means. Active methods typically involve the input of mechanicaland thermal energy to break or melt ice, as well as the application ofsacrificial low surface energy waxes, which all require activeinvolvement of a trained workforce using costly tools andenvironmentally-unfriendly chemicals. Traditional passive methodsinclude low surface energy coatings, but these surfaces are easilyfouled, require maintenance, and tend to be semi-sacrificial.Establishing a surface treatment that required low to no maintenancethat reduced the accretion of ice would result in both economical andecological savings.

Ice accretion, and its adhesion strength, is related to many factorstied to the source of water, as well as the energy of the surface andthe droplet. Atmospheric icing, an issue of great importance toaerospace applications, is extremely difficult to resolve. Resultingfrom their high purity, water droplets in clouds can be found assuper-cooled liquid with temperatures reaching as low as −40° C. Uponthe high velocity impact to an airplane, the super-cooled waterinstantly begins ice nucleation, and the surface of the airplane isfouled.

At lower elevations, ground precipitation becomes a problem. Snow, rain,ice pellets, freezing rain, and the combinatory precipitation of thepreviously listed foul the surfaces of ground infrastructure. Though notas extreme as the high velocity impact of super-cooled liquid withatmospheric icing on planes, ground precipitation becomes more of anissue due to the scale of the problem. Lastly, the formation of ice bycondensation of ambient moisture as frost must be addressed. Althoughthe ice layer associated with frost is typically thinner than theaccretion developed through the previously listed sources, frost hasgreater adhesion to the surface due to its deposition throughout therecesses of a surface.

Partially listed above, the factors that affect ice adhesion arenumerous and are related to a combination of the environment and thesurface characteristics-. Beginning with environmental factors, theambient temperature and humidity have been shown to affect ice adhesion.Impact velocity, droplet size, and wind speed were shown to affect iceadhesion through the droplet kinetics. Relating to both the drop and theenvironment, the ice nucleation and freezing rate were found to affectice adhesion. Finally, as mentioned before, the type of icing hasserious affects on the strength of ice on a surface.

Moving to the surface characteristics, which are the focus of this work,and the use of superhydrophobic surfaces for anti ice accretion, thehydrophilicity or hydrophobicity of a surface affects ice adhesion. Thisattraction, related to the surface energy of the surface, typically hasbeen characterized through contact angle measurement, with a contactangle below 90° being hydrophilic, and a contact angle larger than 90°being hydrophobic.

Superhydrophobic surfaces represent one approach, exhibiting a surface'sability to shed water droplets due to a static contact angle greaterthan 150° and a low contact angle hysteresis. This effect is named afterthe lotus leaf, which exhibits this behavior due to a low surface energywax, as well as a hierarchal roughness of nanometer and micrometerasperities. Many research groups have fabricated surfaces similar to thelotus leaf in order to reproduce the water shedding effect, withcomparable performance.

In order to fabricate the superhydrophobic surface, a variety oftechniques have been used through the literature. These techniquesinclude top-down subtractive methods: optical lithography, e-beamlithography, soft lithography, nanoimprint lithography, block copolymerlithography, scanning probe lithography, and plasma etching, as well asbottom-up additive methods: sol-gel nanofabrication, molecularself-assembly, vapor phase deposition, embedded nanoparticles of silicain epoxy mixture, carbon nanotubes in thermoplastic, cast silica/POSS influoroalkylsilane, and silanized calcium carbonate in polyacrylate. Nomatter which techniques or base substrates were employed, each methodincluded micro/nanometer features for roughness and a low surface energycoating.

Although many research groups have worked on the creation ofsuperhydrophobic surfaces, the focus of their use against ice accretionhas been studied by just a few. Tourkine and his group. compared theeffect of superhydrophobicity on the freezing of static water dropletscompared to hydrophilic surfaces By comparing a fluorinated thioltreated microstructured copper substrate versus a smooth coppersubstrate, a delay in freezing time was observed when using asuperhydrophobic surface. The argued reasoning for this freeze delay wasthe presence of an air film between the droplet and the superhydrophobicsurface, providing insulation to the droplet. Coupled with theself-cleaning properties of superhydrophobic surfaces, the probabilityincreases for the water droplet to be shed prior to adhering to thesurface. In 2010, Yin et al. showed surface wetting for surfaces, fromsuperhydrophilic to superhydrophobic, were temperature-dependent. As theambient testing temperature was reduced from 40° to −10° C., greaterwettability change was shown on the superhydrophobic surface on ahorizontal surface. Although there was greater change associated withsuperhydrophobic surfaces, the paper also looked at varying inclinationangle during ice accretion. Because the superhydrophobic surface wasable to shed the super-cooled water spray, the amount of ice accretionwas significantly decreased with increased inclination angle andhydrophobicity. In Antonini et al., a superhydrophobic etched aluminumsurface coated with Teflon was found to reduce the amount of run-backice as compared to the untreated aluminum surface and a hydrophobic PMMAcoated aluminum surface, designed to replicate the airfoil of anairplane wing. Although the superhydrophobic surface did develop an icelayer, it showed a reduction in energy required to remove ice accretion.The reasoning for the reduced run-back ice was again linked to theability of the surface to shed water droplets, as well as a reducedwetting trail of the droplet on the surface during roll-off. Alizadeh etal. discovered a delay in ice nucleation when comparing superhydrophobicsurfaces versus superhydrophilic, hydrophilic, and hydrophobic surfaces.Using a dynamic droplet, and high-speed photography, superhydrophobicsurfaces were found to have dual means of increasing the time of icenucleation—they affirmed the reduced heat transfer by means of an airbarrier below the droplet that Tourkine noted, as well as suggesting areduced nucleation initiation between the droplet and the surface due toan increase in nucleation activation energy to form a nucleating site.Additionally, the superhydrophobic surface provided a more elasticresponse of the droplet upon impact as compared to the other surfaces.

Mishchenko et al. showed that the adhesion strength of ice on thesurface of a superhydrophobic surface resulting for static freezing wasmuch less than that of the compared surfaces. Further, the retraction ofthe droplet upon impact of a superhydrophobic surface was shown toprovide an additional means of removal prior to ice nucleation. In thestudy a variety of superhydrophobic surfaces were made usingnanostructured silicon arrays, treated with a hydrophobic silane. Thenanostructures were selected to see the dynamic pressure stability ofthe different structures and their effect on impacted dropletretraction. Closed cell structures were found to have better pressurestability, and a reduction in energy loss during droplet retraction.Kulinich and coworkers showed in 2009 that the strength of ice adhesionwas less linked to the static contact angle, and was more of a functionof the contact angle hysteresis. By using a centrifugal ice shearstrength test, the ice adhesion was measured to see its comparison toboth contact angle and contact angle hysteresis.

While much has been reported on the use of superhydrophobic surfaces foranti ice accretion, several research groups suggest against the use ofsuperhydrophobic surfaces due to their inherent roughness; an essentialcharacteristic of superhydrophobic surfaces since the highest contactangle that would result from a smooth surface is on the order of 120°.

Previously mentioned is the ability for superhydrophobic surfaces tosupport water droplets from impinging the surface, typically describedas being in the Cassie-Baxter state; however, with sufficient energy,the water droplet may be impaled by the surface asperities. This stateis typically described as the Wenzel state. Once the droplet is impaledonto a surface, either by the kinetics of the droplet or the asperitypitch of the surface features increasing too much to support the Laplacepressure of the static droplet, the ice formed would again bestrengthened by the increase in contacted surface area.

A further issue related to the features of superhydrophobic roughness isthe cycling of icing and deicing. Kulinich showed that the repeatedprocess of a passive anti-icing surface lost its effectiveness aftereach cycle, questioning the durability of these features. Due to thehigh aspect ratio of the features, the brittle cleaving of the featureschanges the characteristics of the surface.

Although there exists several hurdles with the use of superhydrophobicsurfaces for use in passive anti ice accretion applications, includingbut not limited to: cyclic fracture of surface features and theincreased adhesion due to contacted surface area from the transitionbetween the Cassie-Baxter and Wenzel states and frost formation, the useof superhydrophobic surfaces should not be ruled out as a possiblesolution to anti icing.

The route to obtaining the superhydrophobicity is through thecombination of the surface geometry and chemical functionalization ofthe silane. Prior work has demonstrated the potential for preparation ofsuperhydrophic surfaces from combinations of silica, silanes, and POSS.Rios et al (Transparent Ultra-hydrophobic Coating) showed a contact andsliding angle of above 165° and less than 1° could be achieved with twocoating solutions. The coatings were composed of hydrophilic fumedsilica (Aerosil 200) and fluoro-functionalized polyhedral oligomericsilsesquioxane (FPOSS). The concentration ratios of Aerosil 200 andFPOSS in the two solutions were 1% wt. to 3% wt. and 0.5% wt. to 1.5%wt., respectively. Rios et al. previously tested multipleultra-hydrophobic coatings for durability under multiple conditions.Many aspects of durability were tested including QUV stability, waterimmersion, isopropyl alcohol (IPA) immersion, and paper rubbing. One ofthe best performing coatings was the UH2 comprised of hydrophobicdimethyl-silicone treated fumed silica (Cab-O-Sil TS720) and Dynasylan F8263. The coatings, while demonstrating good icephobic characteristics,were not durable and were easily removed. Thus, there exists a need fora durable and low maintenance coating providing icephobiccharacteristics.

BRIEF SUMMARY

Formulations used in durable and low maintenance coatings providingicephobic and superhydrophobic, self-cleaning characteristics, objectshaving coatings resulting from the formulations and methods forobtaining those coatings are disclosed herein below.

In one or more embodiments, an object having a superhydrophic,self-cleaning, and icephobic coating of these teachings includes asubstrate and a layer disposed on the substrate, the layer resultingfrom coating with a formulation having an effective amount ofmicrostructuring microparticles, liquid silane having one or more groupsconfigured to graft to a microstructuring microparticle and at leastanother group that results in hydrophobicity, the microstructuringmicroparticles being dispersed in the liquid silane and anothereffective amount of synthetic adhesive selected from thermosettingadhesives, moisture curing adhesives or polymers that form a stronginteraction with a surface; the synthetic adhesive being in solutionwith a solvent, the synthetic adhesive being in solution with a solvent,wherein, upon curing, the layer has a contact angle greater than 150°and a sliding angle of less than 10° and, less than 18% of an area ofthe layer and preferably less than 5%, is removed in a Tape test.

In one or more embodiments, the icephobic coating formulation of theseteachings includes an effective amount of microstructuringmicroparticles, liquid silane having one or more groups configured tograft to a microstructuring microparticle and at least another groupthat results in hydrophobicity, the microstructuring microparticlesbeing dispersed in the liquid silane, and another effective amount ofsynthetic adhesive selected from thermosetting adhesives, moisturecuring adhesives or polymers that form a strong interaction with asurface; the synthetic adhesive being in solution with a solvent,wherein, upon mixing the effective amount of microstructuringmicroparticles suspended in the liquid silane with said anothereffective amount of synthetic adhesive dissolved in the solvent andcoating on a substrate and curing, a layer that has a contact anglegreater than 150° and a sliding angle of less than 10°, less than 18% ofan area of the layer and preferably less than 5% of an area of thelayer, is removed in a Tape test is obtained.

In one or more embodiments, the method of these teachings for obtainingan icephobic durable coating includes forming a first solution bysuspending an effective amount of microstructuring microparticles inliquid silane; the liquid silane having one or more groups configured tograft to a microstructuring microparticle and at least another groupthat results in hydrophobicity, stirring the first solution for a firstpredetermined time, the first predetermined time selected such that themicrostructuring microparticles react with the liquid silane, forming asecond solution by dissolving another effective amount of syntheticadhesive in a solvent; the synthetic adhesive being selected fromthermosetting adhesives, moisture curing adhesives, radiation curingadhesives or polymers that form a strong interaction with a surface,mixing the first solution with the second solution in predeterminedproportions; resulting in a third solution, coating a substrate with thethird solution, allowing evaporation of excess solvent in the thirdsolution coated on the substrate, and curing the third solution coatedon the substrate by heating for a second predetermined time at apredetermined temperature or at exposed to a predetermined radiation fora third predetermined time.

Other embodiments are also disclosed.

For a better understanding of the present teachings, together with otherand further objects thereof, reference is made to the accompanyingdrawings and detailed description and its scope will be pointed out inthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical schematic representation of one embodiment of anobject having a superhydrophobic, self-cleaning, and icephobic coatingof these teachings;

FIGS. 1a-1d show exemplary embodiments of silanes as used in theseteachings;

FIG. 2 is a flow diagram representation of one embodiment of the methodof these teachings for assembling an icephobic coating formulation;

FIG. 3 is a flow diagram representation of one embodiment of the methodof these teachings for obtaining an icephobic durable coating;

FIG. 4 is a schematic graphical representation of one embodiment of thecoating product of these teachings;

FIG. 5 shows ATR absorption spectrum of a synthetic adhesive used in oneembodiment of the formulation of these teachings;

FIG. 6 shows ATR absorption spectrum of a silane used in one embodimentof the formulation of these teachings;

FIG. 7 shows ATR absorption spectrum of silica nanoparticles used in oneembodiment of the formulation of these teachings;

FIG. 8 shows ATR absorption spectrum of one embodiment of a coating ofthe formulation of these teachings after different vacuum curingconditions; and

FIG. 9 shows ATR absorption spectrum of one embodiment of a coating ofthe formulation of these teachings after different heat curingconditions.

DETAILED DESCRIPTION

The following detailed description presents the currently contemplatedmodes of carrying out these teachings. The description is not to betaken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of these teachings.

As used herein, the singular forms “a,” “an,” and “the” include theplural reference unless the context clearly dictates otherwise.

Except where otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.”

In order to elucidate the present teachings, the following definitionsare provided.

The “contact angle,” as used herein, is the angle where a liquid/vaporinterface meets a solid surface.

The “sliding angle,” as used herein, is the angle between the samplesurface and the horizontal plane at which the liquid drop starts toslide off the sample surface under gravity influence.

A “Tape Test,” as used herein, is a test using pressure sensitive tapeto determine the adhesion quality of materials (see, for example,IPC-TM-650 for materials used in Printed Boards or ASTM D3359).

“Liquid silane,” as used herein, refers to silane in solution with asolvent, for example, but not limited to, isopropyl alcohol.

“Synthetic adhesives,” as used herein, are adhesives based onelastomers, thermoplastics, emulsions, and thermosets and includepolymers that form a strong interaction with the surface such as, butnot limited to, a thermoplastic polyurethane elastomer, and radiationcurable polymers. Exemplary embodiments of synthetic adhesive arecyanoacrylate, acrylic polymers, thermoplastic polyurethane elastomersand radiation curable polymers.

Formulations used in durable and low maintenance coatings providingicephobic and superhydrophobic, self-cleaning characteristics, objectshaving coatings resulting from the formulations and methods forobtaining those coatings are disclosed herein below.

In one or more embodiments, the icephobic coating formulation of theseteachings includes an effective amount of microstructuringmicroparticles, liquid silane having one or more groups and at leastanother group that results in hydrophobicity, the microstructuringmicroparticles being dispersed in the liquid silane, and anothereffective amount of synthetic adhesive selected from thermosettingadhesives, moisture curing adhesives, radiation curing adhesives orpolymers that form a strong interaction with a surface; the syntheticadhesive being in solution with a solvent, wherein, upon mixing theeffective amount of microstructuring microparticles suspended in theliquid silane with said another effective amount of synthetic adhesivedissolved in the solvent and coating on a substrate and curing, a layerthat has a contact angle greater than 90° (a layer that has a contactangle greater than 150° would be super hydrophobic and preferable) asliding angle of less than 10°, less than 18% of an area of the layerand preferably less than 5% of an area of the layer, is removed in aTape test is obtained. (The relative adhesion strength is quantified bythe light transmission through the tape before and after the test. Thelight transmission can be correlated to the amount of area of the layerthat is removed in the Tape test. See, for example, G. V. Calder, F. C.Hansen, A. Parra, Quantifying the Tape Adhesion Test, in AdhesionAspects of Polymeric Coatings, 1983, Springer Verlag, pp 569-582, whichis incorporated by reference herein in its entirety and for allpurposes.)

In one instance, the liquid silane includes a fluoroalkylsilane or analkylsilane. In one embodiment, the fluoroalkyl silane istridecafluorooctyl-triethoxy silane. Exemplary embodiments of silanes asused in the present teachings are shown in FIGS. 1a-1d . Referring toFIGS. 1a-1d , each silane has one or more groups 35 configured to graftto a microstructuring microparticle and at least another group 45 thatresults in hydrophobicity. (See, for example, these teachings not beinglimited only to that example, Damian Ambrozewicz, Filip Ciesielczyk,Magdalena Nowacka, et al., “Fluoroalkylsilane versus Alkylsilane asHydrophobic Agents for Silica and Silicates,” Journal of Nanomaterials,vol. 2013, Article ID 631938, 13 pages, 2013. doi:10.1155/2013/631938,which is incorporated by reference herein in its entirety and for allpurposes.) In one instance, one or more groups configured to graft to amicrostructuring microparticle are one or more tri-ethoxy groups.

In one instance, the synthetic adhesive is cyanoacrylate. In oneembodiment, the cyanoacrylate is ethyl 2-cyanoacrylate. Other possiblecyanoacrylates include, but are not limited to, methyl 2-cyanoacrylate,n-butyl cyanoacrylate and 2-octyl cyanoacrylate. In one instance, thesolvent used with the synthetic adhesive is acetone. Solvents can alsoinclude, but are not limited to, nitromethane, diethyl ether, hexane,dimethyl sulfoxide, methylene chloride and chloroform. Other instancesof the synthetic adhesive include acrylic polymers, thermoplasticpolyurethane elastomers and radiation curable polymers.

In one instance, the microstructuring microparticles are silicamicroparticles. In one embodiment, the silica microparticles arehydrophobic fumed silica nanoparticles. The silica microparticles canalso include a precipitated silica, unprecipitated silica, hydrophilicfumed silica, colloidal silica or treated colloidal silica. In oneembodiment, the silica microparticles are surface modified withsilicone. In one instance the silicone is polydimethylsiloxane. Thesilica microparticles act as micro-structuring agents. Other embodimentsof micro-structuring agents including, but not limited to,microparticles that are surface modified with silicone where, forexample, the microparticles include treated colloidal silica, silicate,treated silicate, PTFE micropowder, metal nanopowder, or metal oxide arealso within the scope of these teachings.

Exemplary embodiments of metal oxide microparticles are zirconia (ZrO₂)and titania (TiO₂) microparticles (see, for example, these teachings notbeing limited only to those examples, Structure and properties offluoroalkylsilane treated nano-titania Chemeca 2011: Engineering aBetter World: Sydney Hilton Hotel, NSW, Australia, 18-21 Sep. 2011, andGrafting of ZrO₂ powder and ZrO₂ membrane by fluoroalkylsilanes,Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume243, Issues 1-3, 20 Aug. 2004, Pages 43-47, both of which areincorporated by reference herein in their entirety and for allpurposes).

Since the microparticles can be modified in order to enhance theaffinity for grafting or bonding to the one or more groups in thesilane, after modification, a wide number of possibilities ofmicroparticles are within the scope of these teachings. Thecharacteristic dimension (such as, for example, a diameter in asubstantially spherical particle) of the micro-structuringmicroparticles can range from 0.03 micrometers to 5 micrometers orhigher, the range of characteristic dimensions being determined by thesurface roughness necessary in order to achieve superhydrophobicbehavior (see, for example, these teachings not being limited only tothat example, Fluorine Based Super Hydrophobic Coatings, Appl. Sci.,2012, 2, 453-464, which is incorporated by reference herein in itsentirety and for all purposes). In one instance, the range is preferablyfrom 0.1 μm to 0.3 μm or from 0.05 μm to 0.3 μm.

In one instance, the effective amount of silica microparticles isbetween about 0.5% weight and about 5% weight when dispersed in theliquid silane. In another instance, the effective amount is betweenabout 2% weight and about 5% weight. In yet another instance, theeffective amount is between greater than 2% weight and about 5% weight.

In one instance, the other effective amount of synthetic adhesive isbetween about 10% to about 50% by weight when in a solution with asolvent, such as the solvents disclosed herein above. The othereffective amount of synthetic adhesive dissolved in the solvent (orequivalently, the amount of solvent) is selected in order to obtain alayer (film) on the substrate of a desired thickness.

In one instance of the method for assembling the icephobic coatingformulation or the method for making an object having a layer resultingfrom the icephobic coating formulation, at the above described effectiveand other effective amount concentrations, equal volumes of the twomixtures are mixed to make a final coating mixture. This coating mixturehas a ratio of silane coated silica microparticles to adhesive to give acured and dried coating which is superhydrophobic and robust. In otherinstances of the above referred to methods, the effective amount and theother effective amount correspond to concentrations different from thoseof the above described instances are mixed in volumes that result in aratio of silane coated silica microparticles and adhesive similar(within 30%, preferably within 10%) to the ratio resulting when equalvolumes of the above described mixtures are used.

In one embodiment, curing of the icephobic coating formulation, whencoated on a substrate, includes heating for a predetermined time at apredetermined temperature. In one instance, the predetermined time isbetween about 30 min and about 120 min and the predetermined temperatureis between about 65° C. and about 110° C. In another instance, thepredetermined temperature is between about 90° C. and about 110° C. Inyet another instance, the predetermined temperature is between 65° C.and 80°. In one embodiment, curing includes heating for a predeterminedtime at a predetermined temperature in the presence of atmospherichumidity, preferably, but not limited to, where the ambient relativehumidity is between about 40% to about 60%. In another instance, curingincludes remaining at room temperature (RT) for a second predeterminedtime, where the predetermined time can be up to about 24 hours.

In other embodiments, when radiation curable adhesives are used as thesynthetic adhesive, curing includes the application of radiation asnecessary to cure the radiation curable polymer. In one instance, theradiation is applied for a predetermined time. In one embodiment of thepredetermined time is between about 2 min. to about 4 min.

In one or more embodiments, an object having a superhydrophic,self-cleaning, and icephobic coating of these teachings includes asubstrate and a layer disposed on the substrate, the layer resultingfrom coating with the icephobic coating formulation of these teachingsare disclosed herein above. A number of possible embodiments of theobject are obtained from the instances and embodiments of the icephobiccoating formulation as disclosed herein above. Although exemplaryembodiments presented hereinbelow refer to a specific substrate, itshould be noted that other substrates, such as, but not limited to,glass, a polymer, a transparent polymer, a polycarbonate, apolymethylmethacryate, a polyethyleneterephtalate, apoly-ethylenetherftalateglycol, a polysulphone or any modification,combination, copolymer and/or blend thereof a ceramic, a metal, wood,concrete, textiles or leather, are within the scope of these teachings.

FIG. 1 shows a schematic graphical representation of an embodiment ofthe coated object of these teachings. Referring to FIG. 1, in theembodiment shown there in, a substrate 10 has a layer 20 disposedthereon, the layer resulting from coating with the icephobic coatingformulation disclosed herein above.

In one or more embodiments, the method of these teachings for assemblingan icephobic coating formulation includes forming a first solution bysuspending an effective amount of microstructuring microparticles inliquid silane; the liquid silane having one or more groups configured tograft to a microstructuring microparticle and at least another groupthat results in hydrophobicity, stirring the first solution for a firstpredetermined time, the first predetermined time selected such that themicrostructuring microparticles react with the liquid silane, forming asecond solution by dissolving another effective amount of syntheticadhesive in a solvent; the synthetic adhesive being selected fromthermosetting adhesives, moisture curing adhesives or polymers that forma strong interaction with a surface, and mixing the first solution withthe second solution in predetermined proportions.

A number of possible embodiments of the method are obtained from theinstances and embodiments of the icephobic coating formulation asdisclosed herein above. As stated above, in one instance, themicro-structuring microparticles are silica nanoparticles or modifiedsilica nanoparticles. A variety of other particles, as stated above, arealso within the scope of these teachings. In one instance, the liquidsilane includes a fluoroalkyl silane. In other instances, the liquidsilane can include alkylsilanes or aminosilanes. In one embodiment, thefluoroalkyl silane is tridecafluorooctyl-triethoxy silane. In oneinstance, the synthetic adhesive is cyanoacrylate. In one embodiment,the cyanoacrylate is ethyl 2-cyanoacrylate. In one instance, the solventused with the synthetic adhesive is acetone. Solvents can also includenitromethane, diethyl ether, hexane and chloroform. In one instance, thesilica microparticles are hydrophobic fumed silica nanoparticles. Thesilica microparticles can also include precipitated silica,unprecipitated silica, hydrophilic fumed silica, colloidal silica ortreated colloidal silica. In one embodiment, the silica microparticlesare surface modified with silicone. In one instance the silicone ispolydimethylsiloxane. The silica microparticles act as micro-structuringagents. Other embodiments of micro-structuring agents including, but notlimited to, microparticles that are surface modified with siliconewhere, for example, the microparticles include treated colloidal silica,silicate, treated silicate, PTFE micropowder, metal nanopowder, or metaloxide, are also within the scope of these teachings. In one instance,the effective amount of silica microparticles is between about 0.5%weight and about 5% weight when dispersed in the liquid silane. Inanother instance, the effective amount is between about 2% weight andabout 5% weight. In yet another instance, the effective amount isbetween greater than 2% weight and about 5% weight. In one instance, theother effective amount of synthetic adhesive is about 50% by weight whenin a solution with a solvent, such as the solvents disclosed hereinabove. In one instance, the first solution is mixed with the secondsolution in substantially equal portions. The predetermined proportionsused in mixing the first solution was second solution are determined bythe necessary surface roughness to achieve superhydrophobic behavior andthe necessary adhesion of the coating to the surface. As such, thepredetermined proportions are dependent on the effective amount of themicroparticles and the other effective amount of the synthetic adhesive.

FIG. 2 is a flow diagram representation of one embodiment of the methodof these teachings for assembling an icephobic coating formulation.Referring to FIG. 2 in the embodiment shown there in, a first solutionis formed by suspending an effective amount of silica microparticles inliquid silane (step 110), the first solution is stirred for a firstpredetermined time (step 120), a second solution is formed by dissolvinganother effective amount of synthetic adhesive in a solvent (step 130)and the first solution and the second solution are mixed inpredetermined proportions (step 140).

The embodiment of the method of these teachings for assembling anicephobic coating formulation can be assembled in an inert atmosphere.

In another embodiment of method of these teachings for assembling anicephobic coating formulation, the step of mixing the first solutionwith the second solution in predetermined proportions occurs at a timeinterval after (and in some cases different place) the forming of thefirst solution and the forming of the second solution. In one instance,the forming of the first solution and the forming of the second solutionoccur in an inert atmosphere.

In one embodiment, the coating product of these teachings includes asealable container, the sealable container including one embodiment ofthe icephobic coating formulation, where the sealable container isfilled in the inert atmosphere. The sealable container, in one instance,can include desiccants and/or acidic surfaces in order to delay orprevent curing of the synthetic adhesives. In another embodiment, thecoating product of these teachings includes two sealable containers, onesealable container including one embodiment of the first solution andanother sealable container including one embodiment of the secondsolution. The first solution and the second solution are mixed inpredetermined proportions before applying to a substrate.

FIG. 4 shows one embodiment of the coating product of these teachings.Referring to FIG. 4, in the embodiment shown therein, a container 210has a sealable cover 215 and the inside 220 is filled with oneembodiment of the icephobic coating formulation of these teachings. Inother embodiments, the coating product of these teachings includes twocontainers 210, one filled with one embodiment of the first solution andanother one filled with one embodiment of the second solution. Eachcontainer is sealed with one sealable cover 215.

In one or more embodiments, the method of these teachings for obtainingan icephobic durable coating includes forming a first solution bysuspending an effective amount of microstructuring microparticles inliquid silane; the liquid silane having one or more groups configured tograft to a microstructuring microparticle and at least another groupthat results in hydrophobicity, stirring the first solution for a firstpredetermined time, the first predetermined time selected such that themicrostructuring microparticles react with the liquid silane, forming asecond solution by dissolving another effective amount of syntheticadhesive in a solvent; the synthetic adhesive being selected fromthermosetting adhesives, moisture curing adhesives, radiation curingadhesives or polymers that form a strong interaction with a surface,mixing the first solution with the second solution in predeterminedproportions; resulting in a third solution, coating a substrate with thethird solution, allowing evaporation of excess solvent in the thirdsolution coated on the substrate, and curing the third solution coatedon the substrate by heating for a second predetermined time at apredetermined temperature. In those embodiments, the first four stepsassemble the icephobic coating formulation, resulting in the thirdsolution, which is coated on the substrate and cured.

A number of possible embodiments of the method are obtained from theinstances and embodiments of the icephobic coating formulation asdisclosed herein above. As stated above, in one instance, themicro-structuring microparticles are silica nanoparticles or modifiedsilica nanoparticles. A variety of other particles, as stated above, arealso within the scope of these teachings. In one instance, the liquidsilane includes a fluoroalkyl silane. In other instances, the liquidsilane can include alkylsilanes and aminosilanes. In one embodiment, thefluoroalkyl silane is tridecafluorooctyl-triethoxy silane. In oneinstance, the synthetic adhesive is cyanoacrylate. In one embodiment,the cyanoacrylate is ethyl 2-cyanoacrylate. In one instance, the solventused with the synthetic adhesive is acetone. Solvents can also includenitromethane, diethyl ether, hexane and chloroform. In one instance, thesilica microparticles are hydrophobic fumed silica nanoparticles. Thesilica microparticles can also include a precipitated silica,unprecipitated silica, hydrophilic fumed silica, colloidal silica ortreated colloidal silica. In one embodiment, the silica microparticlesare surface modified with silicone. In one instance the silicone ispolydimethylsiloxane. In one instance, the effective amount of silicamicroparticles is between about 0.5% weight and about 5% weight whendispersed in the liquid silane. In another instance, the effectiveamount is between about 2% weight and about 5% weight. In yet anotherinstance, the effective amount is between greater than 2% weight andabout 5% weight. In one instance, the other effective amount ofsynthetic adhesive is about 50% by weight when in a solution with asolvent, such as the solvents disclosed herein above. In one instance,the first solution is mixed with the second solution in substantiallyequal portions. The predetermined proportions used in mixing the firstsolution was second solution are determined by the necessary surfaceroughness to achieve superhydrophobic behavior and the necessaryadhesion of the coating to the surface. As such, the predeterminedproportions are dependent on the effective amount of the microparticlesand the other effective amount of the synthetic adhesive.

FIG. 3 is a flow diagram representation of one embodiment of the methodof these teachings for obtaining an icephobic durable coating. Referringto FIG. 3, in the embodiment shown therein, the first four stepscorrespond to assembling of the icephobic coating formulation, shown inFIG. 2, resulting in a third solution. A substrate is coated with thethird solution (step 150), the excess solvent in the third solutioncoated on the substrate is evaporated (step 160) and the coating is thencured by heating for a second predetermined time at a predeterminedtemperature (step 170).

Coating can be obtained by a variety of methods, ranging from, but notlimited to, dip coating to spin coating, spraying or painting. In oneembodiment, curing of the icephobic coating formulation, when coated ona substrate, comprises heating for a predetermined time at apredetermined temperature. In one instance, the predetermined time isbetween about 30 min and about 75 min and the predetermined temperatureis between about 65° C. and about 110° C. In another instance, thepredetermined temperature is between about 90° C. and about 110° C. Inone instance, the heating for the predetermined time at thepredetermined temperature occurs under atmospheric humidity, preferably,but not limited to, where the ambient relative humidity is between about40% to about 60%.

In order to elucidate these teachings, an exemplary embodiment ispresented herein below. It should be noted that these teachings are notlimited only to that exemplary embodiment.

For the exemplary embodiment, Hydrophobic fumed silica based on alkylsurface treatment, CAB-O-SIL TS720, was supplied by the CabotCorporation (Boston, Mass.). The silica nanoparticles are found inaggregated form, with aggregate length of 0.2-0.3 microns. Atriethoxy(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane inisopropanol solution, Dynasylan F 8263, was supplied by Evonik DegussaInternational AG (Essen, Germany). Ethyl 2-cyanoacrylate was supplied inthe form of Loctite Super Glue Liquid by Henkel (Rocky Hill, Conn.).Reagent grade acetone was purchased from Sigma Aldrich and used asreceived. Studies were conducted on two different substrates,polycarbonate and glass. The polycarbonate sheet and borosilicate glassmicroscope slides were acquired from McMaster-Carr. The polycarbonatesheet had a thickness of 30 mils, and samples were cut to approximately2.54×2.54 cm. The glass slides were a width of 2.2 cm, but not used asacquired. The slides were scribed, roughly 2.54 cm long, using a diamondscribe then broken where scribed.

Each substrate was cleaned with rinsing with isopropyl alcohol (IPA) andkim-wipes, and then dried with compressed argon gas to reduce theresidual moisture on the substrate prior to coating. Two solutions wereindependently prepared—solution A was a 4% by weight Cabosil TS720silica in the Dynasylan F8263 silane solution, while solution B was a50% by weight ethyl 2-cyanoacrylate in acetone solution. Solution A wasstirred using a magnetic stirrer for 1 h, which allowed the silica andsilane to react. Sonication was used during the initial preparationmethodology, however, its use was discontinued after further coatingdevelopment found it an unnecessary step. Once the solutions have mixed,equal parts by volume of solution A and B were mixed for 5 minutes usinga magnetic stirrer just prior to coating. Since the ethyl2-cyanoacrylate component cures via anionic polymerization in thepresence of water, solutions were immediately used after preparation.

The coating methodology varied from substrate dip coating to spincoating though other methods such as painting or spraying could be used.(It should be noted that using the coating in circumstances in whichthere are already in place substrates in the environment would use anapplication method such as painting or spraying) Spin coating showedincreased visual coating uniformity. Spin coating displayed a highly,repeatable coating thickness and was the method used. The solutioncontains a large amount of the solvents. These solvents are dissipatedat a higher rate, but once the spin coating was completed, thesubstrates were covered with an inverted glass petri dish that wastilted to allow for evaporation of the residual. After a half an hour ofevaporation, the sample was placed in a 110° C. oven for 1 h to cure thesilane. A curing kinetics study was conducted to determine this to bethe better curing method of the methods explored. Two milliliters of thefinal solution was spin coated using a CHEMAT Technology KW-4A spincoater on glass substrate for 1 min at 4500 rpm. First set of sampleswas cured in a vacuum (6 mmHg) for 15, 30, 45, and 60 min. Second setwas cured in a vacuum (6 mmHg) for 60 min and then heated in an oven for1 hour at 110° C. Third set was cured in an oven for 1 hour at 110° C.Fourth set was cured at room temperature for 24 hours. All samples wereconditioned at room temperature (RT) before characterization. Theprocedure included the silane cures by removing hydrogen bonding withheat. The heat removes hydrogen bonding in the form of H₂O.

Immediately after curing, the goniometer was used to confirm thecoating's superhydrophobic property. After confirming the static contactangle and sliding angle correlated to superhydrophobicity, topographicalimaging and durability testing were conducted. Topographical imaging wasconducted using a JEOL JSM 6390 Field Emission Scanning ElectronMicroscope (SEM) and a Park PSIA XE-150 Atomic Force Microscope (AFM).The durability testing was evaluated by ASTM D3359-09 Measuring Adhesionby Tape Testing (a visual coating adhesion test that can be enhanced bymeasuring the transmission of light through the tape before and afterthe test).

The curing behavior of the coating is important to obtaining a durableand icephobic coating. The coating was scanned by Attenuated TotalReflectance (IR). FIG. 5 shows characteristic absorption bands of ethyl2-cyanoacrylate arising from stretching of ester C═O, alkene C═C,nitrile C≡N and alkyl C—H at 1730, 1614, 2250, and 2987 cm⁻¹,respectively. Fluoroalkylsilane shows characteristic absorption bandsfor Si—O—CH₂—CH₃, hydrogen bonded Si—OH, Si—O—(CH₂)_(x)—(CF₂)_(x), andSi—O bond from Si—OH and Si—O—Si at 950 and 1127, 3331, 1150, 816 and540 cm⁻¹ respectively (FIG. 6). Ultrahydrophobic silica, Cabot TS720,exhibited characteristic absorption bands of symmetric and asymmetricSi—O stretch, Si—CH₃ and alkyl C—H at 800 and 1071, 1261, and 2980 cm⁻¹,respectively (FIG. 7). In order to understand the reaction mechanism,ATR absorption spectra of the three individual components and thecombination were characterized.

Illustrated in FIG. 8, all sets were cured under vacuum at varyingtimes, and similar absorption peaks shown for all time periods. In thefigure, a low reduction in C═C absorption peak and an increase in Si—Oabsorption peaks result in polymerization.

FIG. 8 showed no significant change in the curing characteristics of thecoating. FIG. 9 demonstrated the absorption peaks for three differentcuring methods. It can be clearly seen in all sets that the C═Cabsorption peak at 1614 cm⁻¹ from ethyl 2-cyanoacrylate disappearedindicating full curing. On the contrary, it was found, in FIG. 9, thatchanges in the absorption spectrum in Set 3 compared to Set 2 and 4derive from elimination of nitrile C≡N and reduction in C═O intensitypeaks. This may be due to the ethyl 2-cyanoacrylate curing mechanism,which is as follows: Ethyl 2-cyanoacrylate adhesives contain an acidicstabilizer, which prevent the molecules from polymerization. As thereaction starts, ambient humidity in the air and on the bonding surfaceneutralized the stabilizer and react with the C═C bond through anionicpolymerization. As can be seen, the C═C absorption peak disappeared inall spectra, and confirmed the polymerization mechanism. However, athigh temperatures and acidic environment the nitrile group is hydrolyzedto carboxylic acid and at the β position readily undergoes thermaldecarboxylation releasing CO₂. This is confirmed by the spectra of FIG.9, Set 3.

Contact angle measurements conform to the ATR results (Table 1). Allsamples that were cured under vacuum and room temperature (RT) exhibitedhydrophilic contact angles (CA<90°) and high sliding angles (SA>90°).This is attributed to the presence of high polar nitrile groups in ethyl2-cyanoacrylate. However, 60 minute curing in vacuum and hightemperature increased significantly contact angle and hydrophobicsurface were obtained (CA>90° and SA<10°) due to partial hydrolysis ofthe polar nitrile group. Better results (CA>150° and SA<10°) wereobtained for high temperature curing under atmospheric humidity, whichallows complete nitrile hydrolysis and decarboxylation. The curingcharacteristics are important for obtaining materials with low slidingangle.

TABLE 1 Effect of Curing Conditions on the Contact and Sliding AnglesSample Contact angle (°) Sliding angle (°) 15 min Vacuum 65-70 >90 30min Vacuum 67-70 >90 45 min Vacuum 70-75 >90 60 min Vacuum 70-75 >90 60min Vacuum + 145-150 50 Heat Heat >150 0 RT Curing 70-75 >90

The Tape test for durability is a visual classifications according topercent of coating removed. The conventional UH2 coating had a ASTM3359-09 Classification of 1B (area of coating removed is 35-65%), andthe coating described in this exemplary embodiment (i.e., in Table 1,the Sample marked Heat, in which the curing occurs in the openatmosphere exposed to humidity) had a classification of 4B (area ofcoating removed is less than 5%). This demonstrates the greaterdurability of the coating of the present teachings.

It should be noted that although these teachings are being illustratedby means of an exemplary embodiment, these teachings are not limited toonly the exemplary embodiment.

For the purposes of describing and defining the present teachings, it isnoted that the term “substantially” is utilized herein to represent theinherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement, or other representation.The term “substantially” is also utilized herein to represent the degreeby which a quantitative representation may vary from a stated referencewithout resulting in a change in the basic function of the subjectmatter at issue.

In order to further elucidate these teachings, three groups of exemplaryembodiments are presented hereinbelow. In the embodiments presentedhereinbelow, different wt % of hydrophobic silica nanoparticles (NPs)were mixed with fluoroalkyl silane (FAS) and stirred for 15 minutes.Different wt % of polymers, acting as synthetic adhesive, were mixed inacetone under nitrogen. Then, the two solutions were mixed by equalweight. 1 ml from the final solution was spin coated on glass substratefor 1 min at 1250 rpm. Each one of the groups of exemplary embodimentshas a given curing prescription.

Table 2 below shows a first group of exemplary embodiments in which thesynthetic adhesive is Ethyl Cyanocrylate. The formulations of the firstgroup are cured at 110° C. for two hours.

TABLE 2 Formulation Ethyl Silica (After Cyanoacrylate Acetone NPs FASWetting mixing) % wt % wt % wt % wt Properties 1 25 25 2.5 47.5Superhydrophobic 2 20 30 2.5 47.45 Superhydrophobic 3 20 30 2 48Superhydrophobic 4 15 35 2.5 47.5 Superhydrophobic 5 15 35 1.5 48.5Superhydrophobic 6 10 40 2.5 47.5 Superhydrophobic 7 10 40 1 49hydrophobic 8 5 45 2.5 47.5 Superhydrophobic 9 5 45 0.5 49.5 hydrophobicSuperhydrophobic wetting properties are characterized by a contact angleabove 150° and sliding below 10°. Hydrophobic wetting properties arecharacterized by a contact angle above 90° and sliding angle above 10°.

Table 3 below shows the second group of exemplary embodiments in whichthe polymer, synthetic adhesive, is urethane acrylate. The formulationsof the second group are cured under a UV lamp for 4 min.

TABLE 3 Formulation Urethane (After Acrylate Acetone Silica NPs FASWetting mixing) % wt % wt % wt % wt Properties 1 25 25 2.5 47.5hydrophobic 2 20 30 2.5 47.45 hydrophobic 3 20 30 2 48 hydrophobic 4 1535 2.5 47.5 hydrophobic 5 15 35 1.5 48.5 hydrophobic 6 10 40 2.5 47.5Superhydrophobic 7 10 40 1 49 hydrophobic 8 5 45 2.5 47.5Superhydrophobic 9 5 45 0.5 49.5 hydrophobic

In instances in which the adhesive is Urethane Acrylate, in someembodiments, the adhesive is between 50 to 65% Mercapto-ester.

Table 4 below shows the third group of exemplary embodiments in whichthe polymer, synthetic adhesive, is epoxy. The formulations of the thirdgroup are cured at 110° C. for two hours.

TABLE 4 Formulation (After Epoxy Acetone Silica NPs FAS Wetting mixing)% wt % wt % wt % wt Properties 1 25 25 2.5 47.5 hydrophobic 2 20 30 2.547.45 hydrophobic 3 20 30 2 48 hydrophobic 4 15 35 2.5 47.5Superhydrophobic 5 15 35 1.5 48.5 hydrophobic 6 10 40 2.5 47.5Superhydrophobic 7 10 40 1 49 hydrophobic 8 5 45 2.5 47.5Superhydrophobic 9 5 45 0.5 49.5 hydrophobic

In instances where the adhesive is epoxy, in some embodiments, Epoxy isPart A (60-100% Bisphenol A diglycidyl Ether resin) Part B (60-100%Trimethylhexane-1,6-diamine) at 20:5 ratio.

Although the present teachings have been described with respect tovarious embodiments, it should be realized these teachings are alsocapable of a wide variety of further and other embodiments within thespirit and scope of the appended claims.

What is claimed is:
 1. A method for obtaining an icephobic durablecoating, the method comprising: forming a first mixture consisting ofmicrostructuring microparticles and a liquid silane, wherein forming thefirst mixture is by suspending an effective amount of microstructuringmicroparticles in liquid silane; the liquid silane having one or moregroups configured to graft to a microstructuring microparticle and atleast another group that results in hydrophobicity; stirring the firstmixture for a first predetermined time, the first predetermined timeselected such that the microstructuring microparticles react with theliquid silane; forming a second mixture by dissolving another effectiveamount of synthetic adhesive in a solvent; the synthetic adhesive beingselected from thermosetting adhesives, moisture curing adhesives, orradiation cured adhesives; mixing the first mixture with the secondmixture in predetermined proportions; resulting in a third mixtureconsisting of 5 to 25 weight percent of the synthetic adhesive, based onthe total weight of the third mixture, the solvent; and the firstmixture after stirring for the first predetermined time; coating asubstrate with the third mixture; and allowing evaporation of excesssolvent in the third mixture coated on the substrate; and curing thethird mixture coated on the substrate by heating for a secondpredetermined time at a predetermined temperature.
 2. The method ofclaim 1 wherein said microstructuring microparticles comprise silicamicroparticles.
 3. The method of claim 2 wherein said one or more groupscomprise one or more tri-ethoxy groups.
 4. The method of claim 2 whereinthe silica microparticles are hydrophobic fumed silica nanoparticles. 5.The method of claim 2 wherein said effective amount is between 0.5%weight and about 5% weight when being dispersed in the liquid silane. 6.The method of claim 2 wherein the effective amount is between 2% weightand about 4% weight when being dispersed in the liquid silane; andwherein said another effective amount is about 50% weight when insolution with the solvent and said solvent is acetone.
 7. The method ofclaim 1 wherein said one or more groups comprise one or more tri-ethoxygroups.
 8. The method of claim 7 wherein the liquid silane comprises afluoroalkyl silane.
 9. The method of claim 8 wherein the liquid silanecomprises tridecafluorooctyl-triethoxy silane.
 10. The method of claim 8wherein the synthetic adhesive is cyanoacrylate.
 11. The method of claim10 wherein the cyanoacrylate is ethyl 2-cyanoacrylate.
 12. The method ofclaim 10 wherein the solvent is acetone.
 13. The method of claim 1wherein the second predetermined time is between 30 min and 75 min andwherein the predetermined temperature is between 80° C. and 110° C. 14.The method of claim 13 wherein the predetermined temperature is between90° C. and 110° C.
 15. The method of claim 1 wherein the predeterminedproportions comprises substantially equal parts of the first mixture andthe second mixture.
 16. The method of claim 1, wherein the liquid silanecomprises an alkyl silane.
 17. A method for obtaining an icephobicdurable coating, the method comprising: forming a first mixtureconsisting of microstructuring microparticles and a liquid silane,wherein forming the first mixture is by suspending an effective amountof microstructuring microparticles in liquid silane; the liquid silanehaving one or more groups configured to graft to a microstructuringmicroparticle and at least another group that results in hydrophobicity;stirring the first mixture for a first predetermined time, the firstpredetermined time selected such that the microstructuringmicroparticles react with the liquid silane; forming a second mixture bydissolving another effective amount of synthetic adhesive in a solvent;the synthetic adhesive being a polymer that interacts with a glass,polymer, ceramic, metal, wood, concrete, textile or leather surface;mixing the first mixture with the second mixture in predeterminedproportions; resulting in a third mixture consisting of 5 to 25 weightpercent of the synthetic adhesive, based on the total weight of thethird mixture, the solvent; and the first mixture after stirring for thefirst predetermined time; coating a substrate with the third mixture,wherein the substrate has a glass, polymer, ceramic, metal, wood,concrete, textile or leather surface; allowing evaporation of excesssolvent in the third mixture coated on the substrate; and curing thethird mixture coated on the substrate by heating for a secondpredetermined time at a predetermined temperature.